Centrifugal blower

ABSTRACT

A centrifugal blower includes a centrifugal fan and a partition cylinder portion. The centrifugal fan includes first blades and second blades arranged about a fan central axis, a separation panel between the first blades and the second blades, and an inward extending part extending inward in a radial direction from the separation panel. The partition cylinder portion has a cylindrical shape extending in an axial direction. The partition cylinder portion is located inside the second blades in the radial direction. The partition cylinder portion partitions air drawn into spaces between the first blades from air drawn into spaces between the second blades. The separation panel has a plate shape extending in the radial direction. The inward extending part is located inside, in the radial direction, both connected ends of the first blades and connected ends of the second blades which are joined to the separation panel.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by referenceJapanese Patent Application No. 2018-058946 filed on Mar. 26, 2018.

TECHNICAL FIELD

The present disclosure relates to a centrifugal blower.

BACKGROUND

A general centrifugal blower of this type includes a centrifugal fanconfigured to simultaneously draw two airflows separated from eachother.

SUMMARY

According to an aspect of the present disclosure; a centrifugal blowerincludes: a centrifugal fan including a plurality of first bladesarranged about a fan central axis, a plurality of second blades arrangedabout the fan central axis, the plurality of second blades being locatedon a first side of the plurality of first blades in an axial directionof the fan central axis and being aligned to the plurality of firstblades, a separation panel located between the plurality of first bladesand the plurality of second blades, and an inward extending partextending inward in a radial direction of the centrifugal fan from theseparation panel; and a partition cylinder portion having a cylindricalshape extending in the axial direction, a diameter of the partitioncylinder portion expanding in the axial direction toward a second sidethat is an opposite side of the first side, the partition cylinderportion being located inside the plurality of second blades in theradial direction. The centrifugal fan is configured to rotate about thefan central axis to: take in air from the first side into spaces betweenthe plurality of first blades and spaces between the plurality of secondblades; blow out the air in the spaces between the plurality of firstblades outward in the radial direction; and blow out the air in thespaces between the plurality of second blades outward in the radialdirection. The partition cylinder portion partitions, on an airflowupstream side of the plurality of first blades and the plurality ofsecond blades, the air taken into the spaces between the plurality offirst blades through an inside of the partition cylinder portion in theradial direction from the air taken into the spaces between theplurality of second blades through an outside of the partition cylinderportion in the radial direction. The separation panel has a plate shapeextending in the radial direction and partitions the air flowing throughthe spaces between the plurality of first blades from the air flowingthrough the spaces between the plurality of second blades. The inwardextending part is located inside, in the radial direction, bothconnected ends of the plurality of first blades each of which is joinedto the separation panel and connected ends of the plurality of secondblades each of which is joined to the separation panel.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure, together with additional objectives, features andadvantages thereof, will be best understood from the followingdescription, the appended claims and the accompanying drawings, inwhich:

FIG. 1 is a cross-sectional diagram schematically illustrating across-section of a centrifugal blower taken by a plane including a fancentral axis, according to a first embodiment;

FIG. 2 is an enlarged view of II part of FIG. 1;

FIG. 3 is a cross-sectional diagram of first blades taken along line ofFIG. 2;

FIG. 4 is a cross-sectional diagram of second blades taken along IV-IVline of FIG. 2;

FIG. 5 is a cross-sectional diagram schematically illustrating acentrifugal blower of a comparative example taken by a plane including afan central axis and corresponding to FIG. 1; and

FIG. 6 is a cross-sectional diagram schematically illustrating acentrifugal blower of a second embodiment taken by a plane including afan central axis and corresponding to FIG. 1.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described hereinafterreferring to drawings. In the embodiments, a part that corresponds to amatter described in a preceding embodiment may be assigned with the samereference numeral, and redundant explanation for the part may beomitted. When only a part of a configuration is described in anembodiment, another preceding embodiment may be applied to the otherparts of the configuration. The parts may be combined even if it is notexplicitly described that the parts can be combined. The embodiments maybe partially combined even if it is not explicitly described that theembodiments can be combined, provided there is no harm in thecombination.

A centrifugal blower is known, which includes a centrifugal fanconfigured to simultaneously draw two airflows separated from eachother, and a first radial band that separates the air blown out of thecentrifugal fan into an airflow on one side and an airflow on the otherside in an axial direction.

The centrifugal fan has multiple blades arranged about a rotation shaft.The first radial band has an annular shape and is located at a centerpart of the blades in the axial direction of the centrifugal fan.

The centrifugal blower includes a separation cylinder that has anapproximately circular cylinder shape and is located inside thecentrifugal fan in a radial direction. The separation cylinder does notrotate and partitions an air intake passage extending from an intakeport to the centrifugal fan into two passages.

In an example of the centrifugal blower, a length of the radial band inthe radial direction of the centrifugal fan is smaller than a length ofthe blade of the centrifugal fan in the radial direction. In such acentrifugal blower, the airs partitioned by the separation cylinder aremixed while the airs flow between the blades.

In another example of the centrifugal blower, a length of the radialband in the radial direction of the centrifugal fan is equal to a lengthof the blade in the radial direction of the centrifugal fan. Thisanother example of the centrifugal blower may limit the airs from mixingin the space between the blades.

However, since there is a gap radially extending between the centrifugalfan that rotates and the separation cylinder that does not rotate, theair may leak through the radially extending gap. Accordingly, the mixingof the airs partitioned by the separation cylinder may cause disturbanceof the airflow toward the blades. Since the radially extending gap isclose to the blades, the disturbed air flows into a space between theblades. The disturbed air flowing into the spaces between the blades maydeteriorate the performance of the fan of the centrifugal blower. Theabove points are recognized as a result of detailed consideration by thepresent inventors.

Embodiments are described below with reference to the drawings. In thefollowing embodiments, identical or equivalent elements are denoted bythe same reference numerals as each other in the figures.

First Embodiment

A centrifugal blower 10 (hereinafter, simply referred to as a “blower10”) of the present embodiment is used in an air-conditioner for avehicle. The blower 10 separates multiple airflows and blows air. Asshown in FIGS. 1, 2, the blower 10 includes a centrifugal fan 12, apartition cylinder portion 14, a fan casing 16, a partition panel 18, anupstream partition wall 20, and a motor 22.

The centrifugal fan 12 is a multi-layer centrifugal fan that rotatesabout a fan central axis CL to draw multiple airflows separated fromeach other from one side in an axial direction DRa of the fan centralaxis CL. In the present embodiment, the axial direction DRa is the axialdirection DRa of the fan central axis CL, i.e. the axial direction DRaof the centrifugal fan 12, the radial direction DRr is the radialdirection DRr of the fan central axis CL, i.e. the radial direction DRrof the centrifugal fan 12. A circumferential direction is thecircumferential direction about the fan central axis CL, i.e. thecircumferential direction of the centrifugal fan 12.

The motor 22 is a driving source that rotates the centrifugal fan 12 ina predetermined fan rotation direction RT (see FIG. 3). The motor 22includes a motor body 221 fixed to the fan casing 16 and a motorrotation shaft 222 protruding from the motor body 221 to the one side inthe fan axial direction DRa. The motor rotation shaft 222 and thecentrifugal fan 12 that is linked to the motor rotation shaft 222 so asnot to rotate relative to the motor rotation shaft 222 rotate in the fanrotation direction RT in response to an energization to the motor 22.

The centrifugal fan 12 includes multiple first blades 121 arranged aboutthe fan central axis CL, multiple second blades 122 arranged about thefan central axis CL, a separation panel 123, a main panel 124, and aside panel 125. The first blades 121, the second blades 122, theseparation panel 123, the main panel 124, and the side panel 125 areintegrated with each other, and accordingly they rotate together aboutthe fan central axis CL.

In the centrifugal fan 12, multiple first blades 121 constitute a firstblowing portion 12 a that sends air using the first blades 121, andmultiple second blades 122 constitute a second blowing portion 12 b thatsends air using the second blades 122. The second blades 122 located onthe one side of the first blades 121 in the fan axial direction DRa.That is, the second blowing portion 12 b is located on one side of thefirst blowing portion 12 a in the fan axial direction DRa to be layered.

Each of the first blades 121 has a first end 121 a that is an end on oneside in the fan axial direction DRa, and a second end 121 b that is anend on the other side in the fan axial direction DRa. Each of the secondblades 122 has a first end 122 a that is an end on the one side in thefan axial direction DRa, and a second end 122 b that is an end on theother side in the fan axial direction DRa.

The main panel 124 of the centrifugal fan 12 has a circular disk shapeextending in the fan radial direction DRr. A motor rotation shaft 222 isconnected to a center part of the main panel 124. The second end 121 bof the first blade 121 is fixed to the main panel 124 at a part that islocated on a radially outer side compared to the connection part of themain panel 124 and the motor rotation shaft 222.

Since the first blades 121 and the second blades 122 are provided insuch manner, the centrifugal fan 12 takes in air from the one side inthe fan central axis DRa and discharges the intake air radially outwardby rotating about the fan central axis CL. In detail, the centrifugalfan 12 rotates about the fan central axis CL to take in air from the oneside in the fan axial direction DRa into the spaces between the firstblades 121 and the spaces between the second blades 122. Simultaneously,the centrifugal fan 12 blows out the intake air in the space between thefirst blades 121 and the space between the second blades 122 radiallyoutward.

Taking in air into the space between the first blades 121 corresponds totaking in air into the first blowing portion 12 a. Similarly, taking inair into the space between the second blades 122 corresponds to takingin air into the second blowing portion 12 b. Blowing out the intake airin the space between the first blades 121 radially outward correspondsto blowing out the intake air in the first blowing portion 12 a outwardin a radial direction of the first blowing portion 12 a. Similarly,blowing out the intake air in the space between the second blades 122radially outward corresponds to blowing out the intake air in the secondblowing portion 12 b outward in a radial direction of the second blowingportion 12 b.

The separation panel 123 of the centrifugal fan 12 has a circularannular shape surrounding the fan central axis CL and has a plate shapeextending in the fan radial direction DRr. The separation panel 123 islocated between the first blades 121 and the second blades 122 in thefan axial direction DRa. Accordingly, the first end 121 a of the firstblade 121 and the second end 122 b of the second blade 122 are fixed tothe separation panel 123. That is, the first end 121 a of the firstblade 121 is a connected end joined to the separation panel 123, and thesecond end 122 b of the second blade 122 is also a connected end joinedto the separation panel 123.

In detail, the separation panel 123 has a width in the fan radialdirection DRr enough to be connected to entire part of the first end 121a of the first blade 121 and the second end 122 b of the second blade122. In the present embodiment, the length of the first end 121 a of thefirst blade 121 is larger than the length of the second end 122 b of thesecond blade 122. The separation panel 123 extends in the fan radialdirection DRr to cover the entire part of the first end 121 a of thefirst blade 121. The separation panel 123 extends inward and outwardfrom the second blade 122 in the fan radial direction DRr.

According to this configuration, the separation panel 123 partitions theair flowing through the space between the first blades 121 from the airflowing through the space between the second blades 122, and preventsthe airs from mixing together. The air flowing through the space betweenthe first blades 121 corresponds to air in the first blowing portion 12a, The air flowing through the space between the second blades 122corresponds to air in the second blowing portion 12 b.

The side panel 125 of the centrifugal fan 12 has a circular annularshape about the fan central axis CL. The first ends 122 a andneighboring parts of the second blades 122 are connected to the sidepanel 125.

Each of the first blades 121 has a first leading edge 121 c that is anupstream edge located upstream with respect to the airflow in the spacebetween the first blades 121. Each of the first blades 121 has a firsttrailing edge 121 d that is a downstream edge located downstream withrespect to the airflow in the space between the first blades 121. Thatis, the first leading edge 121 c defines a part of an inlet of an airflow passage defined between the first blades 121, and the firsttrailing edge 121 d defines a part of an outlet of the air flow passage.

Similarly, each of the second blades 122 has a second leading edge 122 cthat is an upstream edge located upstream with respect to the airflow inthe space between the second blades 122. Each of the second blades 122has a second trailing edge 122 d that is a downstream edge locateddownstream with respect to the airflow in the space between the secondblades 122, That is, the second leading edge 122 c defines a part of aninlet of an air flow passage defined between the second blades 122, andthe second trailing edge 122 d defines a part of an outlet of the airflow passage. For example, since the outlet of the air flow passagedefined between the second blades 122 is located on the other side ofthe side panel 125 in the fan axial direction DRa, the second trailingedges 122 d are also located on the other side of the side panel 125 inthe fan axial direction DRa.

The partition cylinder portion 14 has a cylindrical shape extendingalong the fan axial direction DRa, and a diameter of the partitioncylinder portion 14 enlarges toward the other side in the fan axialdirection DRa. Specifically, the partition cylinder portion 14 has acylinder portion 141 and an expanded portion 142 integrated with thecylinder portion 141. The partition cylinder portion 14 is locatedinside the second blades 122 in the fan radial direction DRr, i.e.inside the second blowing portion 12 b.

The cylinder portion 141 of the partition cylinder portion 14 has acylindrical shape extending along the fan axial direction DRa. Indetail, the cylinder portion 141 has a circular cylindrical shape whoseaxis is the fan central axis CL and extends in the fan axial directionDRa.

The expanded portion 142 of the partition cylinder portion 14 extendsfrom the cylinder portion 141 toward the other side in the fan axialdirection DRa, and the diameter of the enlarged portion 142 enlargestoward the other side in the fan axial direction DRa. In detail, thediameter of the expanded portion 142 expands toward the other side inthe fan axial direction DRa such that the other end of the expandedportion 142 extends outward in the fan radial direction DRr.

The air flowing inside the cylinder portion 141 in the fan radialdirection DRr is drawn into the space between the first blades 121. Theair flowing outside the cylinder portion 141 in the fan radial directionDRr is drawn into the space between the second blades 122. That is, thepartition cylinder portion 14 partitions the air flowing into the spacebetween the first blades 121 from the air flowing into the space betweenthe second blades 122 on the airflow upstream side of the blades 121,122.

The partition cylinder portion 14 of the present embodiment continuesfrom a radially inner part of the separation panel 123 of thecentrifugal fan 12 and is integrated with the centrifugal fan 12.Therefore, the partition cylinder portion 14 rotates together with thecentrifugal fan 12. The radially inner part of the separation panel 123in the fan radial direction DRr is connected to the expanded portion 142of the partition cylinder portion 14. In detail, the expanded portion142 of the partition cylinder portion 14 extends inward in the fanradial direction DRr from the radially inner part of the separationpanel 123.

The expanded portion 142 may correspond to an inward extending part 126of the centrifugal fan 12 extending inward in the fan radial directionDRr from the separation panel 123. That is, the partition cylinderportion 14 includes the inward extending part 126 that is a part of thecentrifugal fan 12. The inward extending part 126 is located inside ofboth the first blades 121 and the second blades 122 in the fan radialdirection DRr. In detail, the inward extending part 126 is locatedinside of both the first end 121 a of the first blade 121 and the secondend 122 b of the second blade 122 in the fan radial direction DRr.

The fan casing 16 is a non-rotating member that does not rotate and is acasing that accommodates the centrifugal fan 12. The fan casing 16includes a bell mouth portion 161 that is an air intake portion defininga casing air intake port 16 a through which the air is taken into thecentrifugal fan 12. The bell mouth portion 161 defines a rim of thecasing air intake port 16 a of the fan casing 16. The cross-section ofthe bell mouth portion 161 has an arc shape such that the air outsidethe fan casing 16 smoothly flows into the casing air intake port 16 a.

The casing air intake port 16 a is located on the one side in the fanaxial direction DRa with respect to the centrifugal fan 12, and opens inthe fan axial direction DRa.

The cylinder portion 141 of the partition cylinder portion 14 is locatedinside the bell mouth portion 161 in the fan radial direction DRr. Inthe casing air intake port 16 a, a part inside the cylinder portion 141in the fan radial direction DRr is a first air intake port 16 b, and apart outside the cylinder portion 141 in the fan radial direction DRr isa second air intake port 16 c. Accordingly, the second air intake port16 c is an opening having a circular annular shape surrounding the firstair intake port 16 b.

The air flowing into the fan casing 16 through the first air intake port16 b is drawn into the first blowing portion 12 a through the radiallyinner side of the cylinder portion 141 of the partition cylinder portion14. The air flowing into the fan casing 16 through the second air intakeport 16 c is drawn into the second blowing portion 12 b through theradially outer side of the cylinder portion 141 of the partitioncylinder portion 14.

The fan casing 16 includes a fan surrounding portion 162, and the fansurrounding portion 162 defines a fan surrounding space 162 asurrounding the centrifugal fan 12. The air blown out of the centrifugalfan 12 flows into the fan surrounding space 162 a.

The partition panel 18 having a plate shape whose thickness directioncorresponds to the fan axial direction DRa is provided in the fansurrounding space 162 a. The partition panel 18 is located radiallyoutside the centrifugal fan 12 to have a small gap with the centrifugalfan 12, and the partition panel 18 has an annular shape extending alongan outer circumference of the centrifugal fan 12. A radially outside endof the partition panel 18 is fixed to the fan surrounding portion 162.

The partition panel 18 provided as described above partitions the fansurrounding space 162 a into a first flow-out passage 162 b and a secondflow-out passage 162 c located on the one side of the first flow-outpassage 162 b in the fan axial direction DRa.

The air flowing through the space between the first blades 121, i.e. afirst air flowing radially outward from the first blowing portion 12 a,flows into the first flow-out passage 162 b. The air flowing through thespace between the second blades 122, i.e. a second air flowing radiallyoutward from the second blowing portion 12 b, flows into the secondflow-out passage 162 c.

The partition panel 18 is provided to suppress the first air fromflowing into the second flow-out passage 162 c and to suppress thesecond air from flowing into the first flow-out passage 162 b.Specifically, a position of a radially inner end 18 a of the partitionpanel 18 is aligned to a position of a radially outer end 123 a of theseparation panel 123 of the centrifugal fan 12 in the fan axialdirection DRa. The first air is not necessarily completely preventedfrom flowing into the second flow-out passage 162 c, but it is enoughthat the first air flowing into the second flow-out passage 162 c isreduced. This also is the same as the second air flowing into the firstflow-out passage 162 b.

The first flow-out passage 162 b is a scroll passage that guides the airflowing out of the first blowing portion 12 a in the fan circumferentialdirection to flow out of the blower 10. Similarly, the second flow-outpassage 162 c is a scroll passage that guides the air flowing out of thesecond blowing portion 12 b in the fan circumferential direction to flowout of the blower 10. The air flowing out of the first flow-out passage162 b and the air flowing out of the second flow-out passage 162 c flowthrough different air passages partitioned from each other, even outsidethe blower 10, for example.

A duct 24 for guiding the air to the blower 10 is provided on the oneside in the fan axial direction DRa with respect to the fan casing 16,and the duct 24 is joined to the fan casing 16 on the one side in thefan axial direction DRa. An upstream air passage 24 a guiding the air tothe casing air intake port 16 a is defined inside the duct 24. Theupstream air passage 24 a is located upstream of the first air intakeport 16 b and the second air intake port 16 c with respect to theairflow and is connected to the first air intake port 16 b and thesecond air intake port 16 c.

A filter 26, the upstream partition wall 20, and a front filterpartition wall 28 is provided in the upstream air passage 24 a. Theupstream partition wall 20 is another member separated from thepartition cylinder portion 14 and fixed to the duct 24 or the fan casing16, for example, That is, the upstream partition wall 20 is anon-rotating member.

The upstream partition wall 20 is provided on the one side in the fanaxial direction DRa with respect to the cylinder portion 141 of thepartition cylinder portion 14, and has a cylindrical shape aligned tothe cylinder portion 141 in the fan axial direction DRa. For example,the upstream partition wall 20 of the present embodiment has a circularcylindrical shape coaxial with the cylinder portion 141 of the partitioncylinder portion 14, and a radius of the upstream partition wall 20 isthe same as that of the cylinder portion 141. According to suchconfiguration, the upstream partition wall 20 partitions an air flowinginto the radially inner side of the cylinder portion 141 from an airflowing into the radially outer side of the cylinder portion 141 on theupstream side of the cylinder portion 141.

Since the upstream partition wall 20 is the non-rotating member and thepartition cylinder portion 14 rotates together with the centrifugal fan12, the upstream partition wall 20 is slightly spaced from the cylinderportion 141 so as not to contact the cylinder portion 141 of thepartition cylinder portion 14, The gap between the partition cylinderportion 14 and the cylinder portion 141 is small such that the air onthe radially inner side of the upstream partition wall 20 and the air inthe radially outer side on the radially outer side of the upstreampartition wall 20 are mixed with each other.

The filter 26 is a non-rotating member fixed to the duct 24, forexample, and allows the air to flow to a downstream side afterfiltrating the air. For example, the filter 26 includes nonwoven fabricas a main element.

The filter 26 is located on the one side in the fan axial direction DRawith respect to the upstream partition wall 20. Since the filter 26 islocated upstream of the upstream partition wall 20 with respect to theairflow, the filter 26 filtrates the air flowing toward the centrifugalfan 12, In detail, the filter 26 filtrates both the air flowing towardthe first blowing portion 12 a of the centrifugal fan 12 and the airflowing toward the second blowing portion 12 b.

The upstream partition wall 20 extends to the filter 26 along the fanaxial direction DRa. The upstream partition wall 20 may extend tocontact the filter 26 or to a position close to the filter 26 to have asmall gap between the upstream partition wall 20 and the filter 26.

The front filter partition wall 28 is located on the one side in the fanaxial direction DRa with respect to the filter 26 in the duct 24, andthe front filter partition wall 28 has a cylindrical shape aligned tothe upstream partition wall 20 across the filter 26. In the presentembodiment, the front filter partition wall 28 has a circularcylindrical shape coaxial with the upstream partition wall 20, and aradius of the front filter partition wall 28 is the same as that of theupstream partition wall 20.

The front filter partition wall 28 extends on the other side in the fanaxial direction DRa to the filter 26. Accordingly, a large part of theair flowing through an radially inner side of the front filter partitionwall 28 flows into the radially inner side of the upstream partitionwall 20 through the filter 26. A large part of the air flowing throughan radially outer side of the front filter partition wall 28 flows intothe radially outer side of the upstream partition wall 20 through thefilter 26.

As shown in FIGS. 3, 4, the shape of the first blade 121 is differentfrom the shape of the second blade 122. Specifically, as shown in FIGS.2, 3, the first blade 121 are backward-curved blade that is positionedon the side opposite to the fan rotation direction RT toward the outerside in the fan radial direction DRr. The first blades 121 may curveagainst the fan rotation direction RT. That is, the shape of a turbofanis adopted as the shape of the first blades 121, and the first blowingportion 12 a is a turbofan.

In contrast, as shown in FIGS. 2, 4, the second blade 122 isforward-curved blade that is positioned on the forward direction side inthe fan rotation direction RT toward the outer side in the fan radialdirection DRr. The second blades 122 may curve in the fan rotationdirection RT. That is, the shape of a sirocco fan is adopted as theshape of the second blades 122, and the second blowing portion 12 b is asirocco fan.

As shown in FIGS. 3, 4, the number of the first blades 121 is differentfrom the number of the second blades 122. Specifically, an angle betweenthe first blades 121 having a common endpoint (fan central axis CL) islarger than an angle between the second blades 122 having a commonendpoint (fan central axis CL). The intervals between the first blades121 may be larger than the intervals between the second blades 122. Thatis, the number of the first blades 121 is smaller than the number of thesecond blades 122.

In the present embodiment, the first blades 121 and the second blades122 are different in shape as follows. As shown in FIGS. 1, 2, an innerdiameter D1 i of the first blades 121 whose center is the fan centralaxis CL is smaller than an inner diameter D2 i of the second blades 122.The inner diameter D1 i is a diameter of an imaginary circular cylinderwhose center is the fan central axis CL and which contacts the firstblades 121 on the radially inner side in the radial direction. That is,the inner diameter D1 i is a diameter of an imaginary circular cylinderwhose center is the fan central axis CL and which is inscribed to thefirst blades 121. The inner diameter D2 i of the second blades 122 canalso be explained in the same way.

An outer diameter D2 o of the second blades 122 is smaller than an outerdiameter D1 o of the first blades 121, The outer diameter D1 o is adiameter of an imaginary circular cylinder whose center is the fancentral axis CL and which contacts the first blades 121 on the radiallyouter side in the radial direction. That is, the outer diameter D1 o isa diameter of an imaginary circular cylinder whose center is the fancentral axis CL and which is circumscribed to the first blades 121. Theouter diameter D2 o of the second blades 122 can also be explained inthe same way.

As it can be understood from the differences between the inner diametersD1 i, D2 i and between the outer diameters D1 o, D2 o, a length L1 r ofthe first blade 121 in the fan radial direction DRr is larger than alength L2 r of the second blade 122 in the fan radial direction DRr. Thelength L1 r of the first blade 121 is a radial width of the first blade121 in the fan radial direction DRr, and the length L2 r of the secondblade 122 is a radial width of the second blade 122 in the fan radialdirection DRr. Accordingly, the length L1 r of the first blade 121 canbe calculated, as shown in FIGS. 1, 2, from the following expression: L1r=(D1 o−D1 i)/2. The length L2 r of the second blade 122 can becalculated from the following expression:

L2r=(D2o−D2i)/2.

As shown in FIG. 2, a height HF1 of the first leading edge 121 c in thefan axial direction DRa is smaller than a height HF2 of the secondleading edge 122 c. Further, a height HB1 of the first trailing edge 121d in the fan axial direction DRa is smaller than a height HB2 of thesecond trailing edge 122 d. That is, the first blade 121 is larger inthe fan radial direction DRr and smaller in the fan axial direction DRaas compared to the second blade 122. The first blades 121 and the secondblades 122 are different in shape as described above.

Next, the airflow in the blower 10 will be roughly described below. Whenthe motor 22 rotates the centrifugal fan 12 in the fan rotationdirection RT, a first airflow is generated where the air flowing throughthe filter 26 into the radially inner side of the upstream partitionwall 20 flows into the first flow-out passage 162 b. At the same time, asecond airflow is generated where the air flowing through the filter 26into the radially outer side of the upstream partition wall 20 flowsinto the second flow-out passage 162 c.

In the first airflow, the air in the radially inner side of the upstreampartition wall 20 flows through the radially inner side of the cylinderportion 141 of the partition cylinder portion 14 and flows along theexpanded portion 142 to turn outward in the fan radial direction DRr.The air flowing outward is drawn into the first blowing portion 12 a andthen blown out from the first blowing portion 12 a to the first flow-outpassage 162 b.

In the second airflow, the air in the radially outer side of theupstream partition wall 20 flows through the radially outer side of thecylinder portion 141 of the partition cylinder portion 14 and flowsalong the expanded portion 142 to turn outward in the fan radialdirection DRr. The air flowing outward is drawn into the second blowingportion 12 b and then blown out from the second blowing portion 12 b tothe second flow-out passage 162 c.

In the present embodiment, as shown in FIGS. 1, 2, the length L1 r ofthe first blade 121 in the fan radial direction DRr is larger than thelength L2 r of the second blade 122 in the fan radial direction DRr. Theair drawn into the space between the first blades 121 passes through theinner side in the fan radial direction DRr with respect to the partitioncylinder portion 14, and the air drawn into the space between the secondblades 122 passes through the outer side in the fan radial direction DRrwith respect to the partition cylinder portion 14.

Since the airs flow through different ways, the length L1 r of the firstblade 121 can be made longer. Accordingly, in order to obtain a specificfan performance, the size of the first blade 121 in the fan axialdirection DRa can be made smaller according to the length L1 r of thefirst blade 121. Accordingly, the size of the blower 10 can be smallwithout deterioration of the performance of the blower 10. That is, itis possible to achieve both compactness and high performance of theblower 10.

According to the present embodiment, the inner diameter D1 i of thefirst blades 121 whose center is the fan central axis CL is smaller thanthe inner diameter D2 i of the second blades 122. The air drawn into thespace between the first blades 121 flows through the radially inner sideof the cylinder portion 141 of the partition cylinder portion 14 in thefan radial direction DRr while the air drawn into the space between thesecond blades 122 flows through the radially outer side of the cylinderportion 141 of the partition cylinder portion 14.

Accordingly, the length L1 r of the first blade 121 can be increased byutilizing the difference in the air flowing place, and the height of thefirst blade 121 in the fan axial direction DRa can be decreased withoutincreasing the size of the centrifugal fan 12. In short, it cancontribute to miniaturization of the blower 10.

Since the inner diameter D1 i of the first blade 121 is smaller than theinner diameter D2 i of the second blade 122, it is advantageous tosecure an opening area of the second air intake port 16 c. That is,since the inner diameter D2 i of the second blade 122 is large, an areaof the air passage through which the air flows into the space betweenthe second blades 122 can be secured on the radially outer side of thecylinder portion 141. As a result, the performance of the centrifugalfan 12 can be improved.

According to the present embodiment, the outer diameter D2 o of thesecond blades 122 whose center is the fan central axis CL is smallerthan the outer diameter D1 o of the first blades 121. Accordingly, it iseasy to provide a structure that prevents the air from flowing throughthe gap between the partition plate 18 and the separation panel 123 ofthe centrifugal fan 12 with avoiding interference between the partitionplate 18 and the second blade 122.

It is easy to shape the first blowing portion 12 a into a flat shape inwhich a ratio of the height of the fan to the fan outer diameter issmall without making the inner diameter D1 i of the first blade 121 toosmall. Accordingly, it is possible to secure the width of the expandedportion 142 in the fan radial direction DRr such that the air flowingaround the expanded portion 142 of the partition cylinder portion 14 inthe fan axial direction DRa smoothly turns outward in the fan radialdirection DRr. Accordingly, the size of the centrifugal fan 12 in thefan axial direction DRa can be decreased while suppressing adeterioration of the performance due to the decrease of the innerdiameter D1 i of the first blade 121.

According to the present embodiment, the centrifugal fan 12 includes theseparation panel 123 between the first blades 121 and the second blades122. The separation panel 123 has a plate shape extending in the fanradial direction DRr and partitions the air flowing through the spacebetween the first blades 121 from the air flowing through the spacebetween the second blades 122. Accordingly, since the separation panel123 limits the air in the space between the first blades 121 and the airin the space between the second blades 122 from mixing together, theairflows generated by the centrifugal fan 12 can be adequately keptbeing separated.

Since the mixing of the airs is suppressed, disturbance of the aircaused by the mixing of the airs can be suppressed, and accordingly adecrease in performance of the fan due to the disturbance of the air canbe avoided. Further, avoiding the deterioration of the performance ofthe fan leads to miniaturization of the centrifugal fan 12.

The inward extending part 126 of the centrifugal fan 12 extends inwardin the fan radial direction DRr from the radially inner part of theseparation panel 123. The inward extending part 126 is located inside inthe fan radial direction DRr of both the first end 121 a of the firstblade 121 and the second end 122 b of the second blade 122 joined to theseparation panel 123. Accordingly, the inward extending part 126deflects the air to some extent and partitions the air flowing towardthe space between the first blades 121 from the air flowing toward thespace between the second blades 122 such that the airs are separatelydrawn into the space between the first blades 121 and the space betweenthe second blades 122.

Accordingly, the mixing of the flow of the air flowing toward the spacebetween the first blades 121 and the flow of the air flowing toward thespace between the second blades 122 can be suppressed on the airflowupstream side of the first blades 121 and the second blades 122. Thismakes it possible to suppress the deterioration of the fan performanceof the blower 10.

In the present embodiment, the partition cylinder portion 14 includesthe inward extending part 126 and rotates together with the centrifugalfan 12. That is, the radially inner part of the separation panel 123 inthe fan radial direction DRr is connected to the partition cylinderportion 14. Accordingly, the air flowing on the radially inner side ofthe partition cylinder portion 14 and the air flowing on the radiallyouter side of the partition cylinder portion 14 which are separated fromeach other can be smoothly guided to the first blowing portion 12 a andthe second blowing portion 12 b separately. Accordingly, a generation ofvortices caused by a gap between the separation panel 123 and theexpanded portion 142 of the partition cylinder portion 14 in animaginary configuration in which the separation panel 123 is spaced fromthe expanded portion 142 can be avoided. That is, a decrease inperformance of the fan caused when the vortices are drawn into the spacebetween the first blades 121 or the space between the second blades 122can be avoided.

Advantages of the blower 10 of the present embodiment will be describedwith reference to FIG. 5 showing a blower 90 of a comparative example.In the blower 90 of the comparative example, as shown in FIG. 5, thecentrifugal fan 12 does not include the separation panel 123, and thepartition cylinder portion 14 is a part separated from the centrifugalfan 12 and is a non-rotating member that does not rotate. Accordingly, agap is formed between the expanded portion 142 of the partition cylinderportion 14 and the centrifugal fan 12 to avoid interference duringrotation of the centrifugal fan. The other configurations of the blower90 of the comparative example are the same as the blower 10 of thepresent embodiment.

As described above, since the gap is formed between the expanded portion142 of the partition cylinder portion 14 and the centrifugal fan 12 inthe blower 90 of the comparative example, the air flows through the gapat A1 part of FIG. 5 to mix together. That is, the airflows are justroughly separated. Accordingly, vortices are generated at an end of theexpanded portion 142 defining the gap, and the vortices are drawn intothe blowing portions 12 a, 12 b to deteriorate the performance of thefan.

Further, since the separation panel 123 is not provided in the blower 90of the comparative example, the air in the first blowing portion 12 aand the air in the second blowing portion 12 b may mix together.

In contrast, the blower 10 of the present embodiment includes theseparation panel 123 as shown in FIG. 1, and the separation panel 123 isconnected to the partition cylinder portion 14 without any gaps.Accordingly, the blower 10 of the present embodiment has advantages thatthe mixing of the airflows and the deterioration of the fan performancewhich may occur in the blower 90 of the comparative example can beavoided.

According to the present embodiment, as shown in FIGS. 3, 4, the numberof the first blades 121 is different from the number of the secondblades 122. Accordingly, the first blades 121 and the second blades 122need not be continuous in the fan axial direction DRa, and the firstblade 121 and the second blade 122 may have different shape. Forexample, the shapes of the first blade 121 and the second blade 122 maybe changed according to the lengths L1 r, L2 r.

According to the present embodiment, as shown in FIG. 3, the first blade121 is positioned on the side opposite to the fan rotation direction RTtoward the outer side in the fan radial direction DRr. Thebackward-curved blades are suitable for having a flat shape in which theratio of the height of the fan to the outer diameter is small.Accordingly, the shapes of the first blades 121 are easy to be modifiedsuch that the inner diameter D1 i is small and the length L1 r is large.

According to the present embodiment, as shown in FIG. 4, the secondblade 122 is the forward-curved blade that is positioned on the forwarddirection side in the fan rotation direction RT toward the outer side inthe fan radial direction DRr. The fan having forward-curved blades isbetter than the fan having backward-curved blades to modify the faninner diameter to be large. Accordingly, the shapes of the second blades122 are suitable to secure the air flow area for the air flowing intothe space between the second blades 122. That is, the shapes of thesecond blades 122 are suitable to secure the opening area of the secondair intake port 16 c.

According to the present embodiment, a height HB1 of the first trailingedge 121 d in the fan axial direction DRa is smaller than a height HB2of the second trailing edge 122 d as shown in FIGS. 1, 2. Accordingly, aspace for the first blades 121 in the fan axial direction DRa can besmall in addition to securing the air flow area for the air flowing outof the space between the second blades 122.

According to the present embodiment, a height HF1 of the first leadingedge 121 c in the fan axial direction DRa is smaller than a height HF2of the second leading edge 122 c. Accordingly, a space for the firstblades 121 in the fan axial direction DRa can be small in addition tosecuring the air flow area for the air flowing into the space betweenthe second blades 122.

Further, according to the present embodiment, the partition panel 18partitions the fan surrounding space 162 a into which the air flow fromthe centrifugal fan 12 into the first flow-out passage 162 b and thesecond flow-out passage 162 c located on the one side of the firstflow-out passage 162 b in the fan axial direction DRa. The first airblown out of the space between the first blades 121 flows into the firstflow-out passage 162 b. Simultaneously, the second air blown out of thespace between the second blades 122 flows into the second flow-outpassage 162 c. The partition panel 18 is provided to suppress the firstair from flowing into the second flow-out passage 162 c and to suppressthe second air from flowing into the first flow-out passage 162 b.

Accordingly, the airs partitioned by the partition cylinder portion 14and taken in the centrifugal fan 12 keeps being separated and flow outof the blower 10 from the first flow-out passage 162 b and the secondflow-out passage 162 c separately.

Further, according to the present embodiment, the upstream partitionwall 20 provided as a member separated from the partition cylinderportion 14 on the one side in the fan axial direction DRa with respectto the cylinder portion 141, and has a cylindrical shape aligned to thecylinder portion 141 in the fan axial direction DRa. The upstreampartition wall 20 partitions the air flowing into the inner side of thecylinder portion 141 from the air flowing into the outer side of thecylinder portion 141 on the airflow upstream side of the the cylinderportion 141. The filter 26 filtrating the air flowing toward thecentrifugal fan 12 is located on the one side in the fan axial directionDRa with respect to the upstream partition wall 20, and the upstreampartition wall 20 extends to the filter 26. Accordingly, the air flowingthrough the inside of the cylinder portion 141 and the air flowingthrough the outside of the cylinder portion 141 can be prevented frommixing together between the filter 26 and the partition cylinder portion14, and the partition cylinder portion 14 can be provided without regardto the shape and the position of the filter 26.

Second Embodiment

A second embodiment of the present disclosure is described next. Thepresent embodiment will be explained primarily with respect to portionsdifferent from those of the first embodiment. In addition, explanationsof the same or equivalent portions as those in the above embodiment willbe omitted or simplified. This also applies to the description of theembodiment to be described later.

As shown in FIG. 6, in the present embodiment, the partition cylinderportion 14 is separated from the centrifugal fan 12. That is, thepartition cylinder portion 14 of the present embodiment includes theinward extending part 126 of the centrifugal fan 12. Specifically, thepartition cylinder portion 14 is provided such that the expanded portion142 of the partition cylinder portion 14 is located inside the inwardextending part 126 of the centrifugal fan 12 in the fan radial directionDRr. The partition cylinder portion 14 is a non-rotating member thatdoes not rotate.

Further, in the present embodiment, the upstream partition wall 20 (seeFIG. 1) is not provided. Instead, the partition cylinder portion 14extends to the filter 26 located on the one side in the fan axialdirection DRa with respect to the partition cylinder portion 14. Indetail, the cylinder portion 141 of the partition cylinder portion 14extends to the filter 26 provided on the one side in the fan axialdirection DRa with respect to the cylinder portion 141. This positionalrelationship between the cylinder portion 141 and the filter 26 is thesame as the positional relationship between the upstream partition wall20 and the filter 26 of the first embodiment.

Since the centrifugal fan 12 rotates while the partition cylinderportion 14 is the non-rotating member in the present embodiment, thepartition cylinder portion 14 is slightly separated from the centrifugalfan 12 so as not to interfere with the rotation of the centrifugal fan12.

The partition cylinder portion 14 separates the air flowing into thespace between the first blades 121 from the air flowing into the spacebetween the second blades 122 on the airflow upstream side of the inwardextending part 126 of the centrifugal fan 12. That is, the partitioncylinder portion 14 is provided relative to the centrifugal fan 12 suchthat the air flowing along the expanded portion 142 of the partitioncylinder portion 14 into the first blowing portion 12 a and the airflowing into the second blowing portion 12 b are limited from mixingtogether.

For example, the expanded portion 142 of the partition cylinder portion14 is slightly spaced from the inward extending part 126 of thecentrifugal fan 12. Assuming that the partition cylinder portion 14 isprovided without the gap between the inward extending part 126 and theexpanded portion 142, the partition cylinder portion 14 has a plateshape continuing from the inward extending part 126 to the expandedportion 142. Although less communication of the air through the smallgap between the expanded portion 142 of the partition cylinder portion14 and the inward extending part 126 of the centrifugal fan 12 isbetter, the communication needs not completely shut off.

Aside from the above described aspects, the present embodiment is thesame as the first embodiment. Further, in the present embodiment,effects similar to those of the first embodiment described above can beobtained in the same manner as in the first embodiment.

According to the present embodiment, the partition cylinder portion 14does not include the inward extending part 126 of the centrifugal fan12, but the inward extending part 126 extends inward from the separationpanel 123 in the fan radial direction DRr. The inward extending part 126is located inside, in the fan radial direction DRr, both the first end121 a of the first blade 121 and the second end 122 b of the secondblade 122.

The airs partitioned by the partition cylinder portion 14 may mixtogether through the gap between the expanded portion 142 and the inwardextending part 126, and thereby the airflow may be disturbed. In thiscase, the airflows containing the disturbance and flowing toward theblowing portions 12 a, 12 b are controlled by the inward extending part126, and then the air flows into the space between the first blades 121and the space between the second blades 122. As a result, adeterioration of the fan performance due to the mixing of the airsseparated from each other on the airflow upstream side of the blades121, 122 can be suppressed.

According to the present embodiment, the partition cylinder portion 14is separated from the centrifugal fan 12 and is a non-rotating memberthat does not rotate. Accordingly, it is easy to simplify the structureof the centrifugal fan 12 to improve the productivity of the blower 10as compared with a case where the partition cylinder portion 14 isintegrated with the centrifugal fan 12, for example.

Further, the filter 26 is located on the one side in the fan axialdirection DRa with respect to the partition cylinder portion 14, and thepartition cylinder portion 14 extends to the filter 26. Accordingly, theair flowing toward the radially inner side of the cylinder portion 141and the air flowing toward the radially outer side of the cylinderportion 141 are limited from mixing together on the airflow downstreamside of the filter 26 without any object between the filter 26 and thepartition cylinder portion 14.

Other Embodiments

(1) In the above-described embodiments, the centrifugal fan 12 includesthe first blades 121 and the second blades 122 as shown in FIG. 1, forexample, but this is just an example. For example, the centrifugal fan12 may include multiple third blades and multiple fourth blades alignedto the blades 121, 122 in the fan axial direction DRa in addition to theblades 121, 122. That is, the fan 12 may include multiple blowingportions having multiple blades, and the multiple blowing portions maybe aligned in the fan axial direction DRa.(2) In the above-described embodiments, the shape of the turbofan isused as the shape of the first blade 121 as shown in FIG. 3. However,this is just an example. For example, another shape of a centrifugal fandifferent from the shape of the turbofan may be used as the shape of thefirst blade 121.(3) In the above-described embodiments, the shape of the sirocco fan isused as the shape of the second blade 122 as shown in FIG. 4. However,this is just an example. For example, another shape of a centrifugal fandifferent from the shape of the sirocco fan may be used as the shape ofthe second blade 122.(4) In the above-described embodiments, the filter 26 is located on theairflow upstream side of the centrifugal fan 12 as shown in FIG. 1, forexample. However, the filter 26 may not be provided.(5) In the above-described embodiments, the number of the first blades121 is smaller than the number of the second blades 122 as shown inFIGS. 3, 4. However, this is just an example. For example, the number ofthe first blades 121 may be equal to or larger than the number of thesecond blades 122.(6) The present disclosure is not limited to the specific embodimentsdescribed above, and various modifications can be made. In each of theabove embodiments, it is needless to say that the elements configuringthe embodiment are not necessarily indispensable except when it isclearly indicated that the elements are particularly indispensable, whenthe elements are clearly considered to be indispensable in principle,and the like.

Further, in each of the above embodiments, when numerical values such asthe number, numerical value, quantity, range, and the like of thecomponents of the embodiment are referred to, except in the case wherethe numerical value is expressly indispensable in particular, the casewhere the numerical value is obviously limited to a specific number inprinciple, and the like, the present disclosure is not limited to thespecific number. Furthermore, a material, a shape, a positionalrelationship, or the like, if specified in the above-described exampleembodiments, is not necessarily limited to the specific material, shape,positional relationship, or the like unless it is specifically statedthat the material, shape, positional relationship, or the like isnecessarily the specific material, shape, positional relationship, orthe like, or unless the material, shape, positional relationship, or thelike is obviously necessary to be the specific material, shape,positional relationship, or the like in principle.

CONCLUSION

According to a first aspect described in all or some of theabove-described embodiments, the centrifugal fan includes a separationpanel between the first blades and the second blades. The separationpanel has a plate shape extending in the radial direction and partitionsthe air flowing through the space between the first blades from the airflowing through the space between the second blades. The centrifugal fanincludes inward extending part. The inward extending part extends inwardin the radial direction from the separation panel. The inward extendingpart located inside, in the radial direction, both connected ends of thefirst blades joined to the separation panel and connected ends of thesecond blades joined to the separation panel.

According to this configuration, since the separation panel of thecentrifugal fan limits the air in the space between the first blades andthe air in the space between the second blades from mixing together, theairflows generated by the centrifugal fan can be adequately kept beingseparated.

The inward extending part of the centrifugal fan extends inward in theradial direction from the separation panel, and is located inside, inthe radial direction, both connected ends of the first blades each ofwhich is joined to the separation panel and connected ends of the secondblades each of which is joined to the separation panel. Accordingly, theinward extending part deflects the air to some extent and separates theair flowing toward the spaces between the blades such that the airs areseparately drawn into the space between the first blades and the spacebetween the second blades. Accordingly, the mixing of the flow of theair flowing toward the space between the first blades and the flow ofthe air flowing toward the space between the second blades can besuppressed on the airflow upstream side of the first blades and thesecond blades. This makes it possible to suppress the deterioration ofthe fan performance of the centrifugal blower.

According to a second aspect, the partition cylinder portion includesthe inward extending part and rotates together with the centrifugal fan.That is, the radially inner part of the separation panel in the radialdirection is connected to the partition cylinder portion. Accordingly,the air flowing on the radially inner side of the partition cylinderportion and the air flowing on the radially outer side of the partitioncylinder portion which are separated from each other can be smoothlyguided to the first blades and the second blades. Accordingly, ageneration of vortices caused by a gap between the separation panel andthe partition cylinder portion in an imaginary configuration in whichthe separation panel is spaced from the partition cylinder portion canbe avoided. That is, a decrease in performance of the fan caused whenthe vortices are drawn into the space between the first blades or thespace between the second blades can be avoided.

According to a third aspect, the partition cylinder portion is separatedfrom the centrifugal fan and is a non-rotating member that does notrotate. The partition cylinder portion separates the air flowing intothe space between the first blades from the air flowing into the spacebetween the second blades on the airflow upstream side of the inwardextending part. Accordingly, it is easy to simplify the structure of thecentrifugal fan to improve the productivity of the centrifugal blower ascompared with a case where the partition cylinder portion is integratedwith the centrifugal fan, for example.

According to a fourth aspect, the fan casing that accommodates thecentrifugal fan defines the fan surrounding space that surrounds thecentrifugal fan on the radially outside. The air flows out of thecentrifugal fan into the fan surrounding space. The partition panelpartitions the fan surrounding space in the axial direction into thefirst flow-out passage and the second flow-out passage. The first airblown out of the space between the first blades flows into the firstflow-out passage. In contrast, the second air blown out of the spacebetween the second blades flows into the second flow-out passage. Thepartition panel is provided to suppress the first air from flowing intothe second flow-out passage and to suppress the second air from flowinginto the first flow-out passage. Accordingly, the air partitioned by thepartition cylinder portion and taken in the centrifugal fan keeps beingseparated and flows out of the centrifugal blower from the firstflow-out passage and the second flow-out passage separately.

According to a fifth aspect, the filter that filtrates the air flowingtoward the centrifugal fan is located on the one side of the partitioncylinder portion in the axial direction. The partition cylinder portionextends to the filter. Accordingly, the air flowing toward the radiallyinner side of the partition cylinder portion and the air flowing towardthe radially outer side of the partition cylinder portion are limitedfrom mixing together on the airflow downstream side of the filter.

According to a sixth aspect, the upstream partition wall is separatedfrom the partition cylinder portion and located on the one side of thepartition cylinder portion in the axial direction. The upstreampartition wall has a cylindrical shape aligned to the partition cylinderportion in the axial direction. The upstream partition wall partitionsthe air flowing into the inner side of the partition cylinder portionfrom the air flowing into the outer side of the partition cylinderportion on the airflow upstream side of the partition cylinder portion.The filter filtrating the air flowing toward the centrifugal fan islocated on the one side in the axial direction with respect to theupstream partition wall, and the upstream partition wall extends to thefilter. In this configuration also, similarly to the fifth aspect, theair flowing toward the radially inner side of the partition cylinderportion and the air flowing toward the radially outer side of thepartition cylinder portion are limited from mixing together on theairflow downstream side of the filter.

Although the present disclosure has been fully described in connectionwith the preferred embodiments thereof with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art.

Additional advantages and modifications will readily occur to thoseskilled in the art. The disclosure in its broader terms is therefore notlimited to the specific details, representative apparatus, andillustrative examples shown and described.

What is claimed is:
 1. A centrifugal blower comprising: a centrifugalfan including a plurality of first blades arranged about a fan centralaxis, a plurality of second blades arranged about the fan central axis,the plurality of second blades being located on a first side of theplurality of first blades in an axial direction of the fan central axisand being aligned to the plurality of first blades, a separation panellocated between the plurality of first blades and the plurality ofsecond blades, and an inward extending part extending inward in a radialdirection of the centrifugal fan from the separation panel; and apartition cylinder portion having a cylindrical shape extending in theaxial direction, a diameter of the partition cylinder portion expandingin the axial direction toward a second side that is an opposite side ofthe first side, the partition cylinder portion being located inside theplurality of second blades in the radial direction, wherein thecentrifugal fan is configured to rotate about the fan central axis totake in air from the first side into spaces between the plurality offirst blades and spaces between the plurality of second blades, blow outthe air in the spaces between the plurality of first blades outward inthe radial direction, and blow out the air in the spaces between theplurality of second blades outward in the radial direction, thepartition cylinder portion partitions, on an airflow upstream side ofthe plurality of first blades and the plurality of second blades, theair taken into the spaces between the plurality of first blades throughan inside of the partition cylinder portion in the radial direction fromthe air taken into the spaces between the plurality of second bladesthrough an outside of the partition cylinder portion in the radialdirection, the separation panel has a plate shape extending in theradial direction and partitions the air flowing through the spacesbetween the plurality of first blades from the air flowing through thespaces between the plurality of second blades, and the inward extendingpart is located inside, in the radial direction, both connected ends ofthe plurality of first blades each of which is joined to the separationpanel and connected ends of the plurality of second blades each of whichis joined to the separation panel.
 2. The centrifugal blower accordingto claim 1, wherein the partition cylinder portion includes the inwardextending part and rotates together with the centrifugal fan.
 3. Thecentrifugal blower according to claim 1, wherein the partition cylinderportion is separated from the centrifugal fan and is a non-rotatingmember that is not configured to rotate, and the partition cylinderportion partitions, on an airflow upstream side of the inward extendingpart, the air taken into the spaces between the plurality of firstblades from the air taken into the spaces between the plurality ofsecond blades.
 4. The centrifugal blower according to claim 1, furthercomprising: a fan casing that accommodates the centrifugal fan, the fancasing defining a fan surrounding space that surrounds the centrifugalfan outside the centrifugal fan in the radial direction, the air flowinginto the fan surrounding space from the centrifugal fan; and a partitionpanel that partitions the fan surrounding space in the axial directioninto a first flow-out passage and a second flow-out passage, wherein afirst air flowing out of the spaces between the plurality of firstblades flows into the first flow-out passage, a second air flowing outof the spaces between the plurality of second blades flows into thesecond flow-out passage, and the partition panel is configured to limitthe first air from entering the second flow-out passage and limit thesecond air from entering the first flow-out passage.
 5. The centrifugalblower according to claim 1, further comprising: a filter located on afirst side of the partition cylinder portion in the axial direction tofiltrate the air flowing toward the centrifugal fan, wherein thepartition cylinder portion extends to the filter.
 6. The centrifugalblower according to claim 1, further comprising: an upstream partitionwall located on a first side of the partition cylinder portion in theaxial direction and separated from the partition cylinder portion, theupstream partition wall having a cylindrical shape aligned to thepartition cylinder portion in the axial direction, the upstreampartition wall partitioning the air flowing into the inside of thepartition cylinder portion from the air flowing into the outside of thepartition cylinder portion on an airflow upstream side of the partitioncylinder portion; and a filter located on a first side of the upstreampartition wall in the axial direction to filtrate the air flowing towardthe centrifugal fan, wherein the upstream partition wall extends to thefilter.